System and method for efficient network reconfiguration in fat-trees

A system for supporting efficient reconfiguration of an interconnection network having a pre-existing routing comprising:

• one or more computers which each include one or more microprocessors;
• and
• a network, the network comprising:
• a plurality of switches, each switch comprising a linear forwarding table, of a plurality of linear forwarding tables, each linear forwarding table being configured according to the pre-existing routing, the plurality of switches comprising a plurality of leaf switches,
• a subnet manager, the subnet manager running on one of the plurality of switches, and
• a metabase accessible by the subnet manager, the metabase storing a first set of calculated leaf-switch to leaf-switch multipaths;
• wherein the subnet manager detects a reconfiguration triggering event in the network, the reconfiguration triggering event comprising an event other than a topology change;
• wherein the subnet manager distributes at least one multipath of the first set of one or more leaf-switch to leaf-switch multipaths to the plurality of switches;
• wherein a linear forwarding table of a switch of the plurality of switches is updated, by the subnet manager, according to the distributed at least one multipath of the first set of one or more leaf-switch to leaf-switch multipaths.

A non-transitory computer readable storage medium having instructions thereon for supporting efficient reconfiguration of an interconnection network having a pre-existing routing, which when read an executed cause a computer to perform steps comprising:

• providing one or more computers, wherein each of computer comprises one or more microprocessors;
• providing a network, the network comprising:
• a plurality of switches, each switch comprising a linear forwarding table, of a plurality of linear forwarding tables, each linear forwarding table being configured according to the pre-existing routing, the plurality of switches comprising a plurality of leaf switches,
• a subnet manager, the subnet manager running on one of the plurality of switches, and
• a metabase accessible by the subnet manager, the metabase storing a first set of calculated leaf-switch to leaf-switch multipaths;
• detecting, by the subnet manager, a reconfiguration triggering event in the network, the reconfiguration triggering event comprising an event other than a topology change;
• distributing, by the subnet manager, at least one multipath of the first set of one or more leaf-switch to leaf-switch multipaths to the plurality of switches;
• updating, by the subnet manager, a linear forwarding table of a switch of the plurality of switches according to the distributed at least one multipath of the first set of one or more leaf-switch to leaf-switch multipaths.